<?php

class TranslationRepo
{
    private const TABLE_MAP = [
        'question'      => ['table' => 'question_translation',      'pk' => 'questionID'],
        'answer_option' => ['table' => 'answer_option_translation', 'pk' => 'answerOptionID'],
        'string'        => ['table' => 'string_translation',        'pk' => 'stringKey'],
    ];

    /**
     * @return list<array{languageCode: string, name: string}>
     */
    public static function listLanguages(PDO $pdo): array
    {
        return $pdo->query(
            "SELECT languageCode, name FROM language ORDER BY languageCode"
        )->fetchAll(PDO::FETCH_ASSOC);
    }

    public static function upsertLanguage(PDO $pdo, string $code, string $name): void
    {
        $pdo->prepare("
            INSERT INTO language (languageCode, name) VALUES (:lc, :n)
            ON CONFLICT(languageCode) DO UPDATE SET name = excluded.name
        ")->execute([':lc' => $code, ':n' => $name]);
    }

    /**
     * Delete a language and all its translations across all three tables.
     */
    public static function deleteLanguage(PDO $pdo, string $code): void
    {
        $pdo->prepare("DELETE FROM language WHERE languageCode = :lc")
            ->execute([':lc' => $code]);
        $pdo->prepare("DELETE FROM question_translation WHERE languageCode = :lc")
            ->execute([':lc' => $code]);
        $pdo->prepare("DELETE FROM answer_option_translation WHERE languageCode = :lc")
            ->execute([':lc' => $code]);
        $pdo->prepare("DELETE FROM string_translation WHERE languageCode = :lc")
            ->execute([':lc' => $code]);
    }

    /**
     * Get all translations for a given entity.
     *
     * @param string $type  question|answer_option|string
     * @return list<array{languageCode: string, text: string}>
     */
    public static function getForEntity(PDO $pdo, string $type, string $id): array
    {
        $meta = self::meta($type);

        $stmt = $pdo->prepare(
            "SELECT languageCode, text FROM {$meta['table']} WHERE {$meta['pk']} = :id"
        );
        $stmt->execute([':id' => $id]);

        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Insert or update a single translation.
     *
     * @param string $type  question|answer_option|string
     */
    public static function upsert(PDO $pdo, string $type, string $id, string $lang, string $text): void
    {
        $meta = self::meta($type);

        $pdo->prepare("
            INSERT INTO {$meta['table']} ({$meta['pk']}, languageCode, text)
            VALUES (:id, :lang, :t)
            ON CONFLICT({$meta['pk']}, languageCode) DO UPDATE SET text = excluded.text
        ")->execute([':id' => $id, ':lang' => $lang, ':t' => $text]);
    }

    /**
     * Delete a single translation.
     *
     * @param string $type  question|answer_option|string
     */
    public static function delete(PDO $pdo, string $type, string $id, string $lang): void
    {
        $meta = self::meta($type);

        $pdo->prepare(
            "DELETE FROM {$meta['table']} WHERE {$meta['pk']} = :id AND languageCode = :lang"
        )->execute([':id' => $id, ':lang' => $lang]);
    }

    /**
     * @return array{table: string, pk: string}
     */
    private static function meta(string $type): array
    {
        if (!isset(self::TABLE_MAP[$type])) {
            throw new InvalidArgumentException("Unknown translation type: $type");
        }

        return self::TABLE_MAP[$type];
    }
}